The present invention relates to a cutting tool and relates more particularly, but not exclusively, to a cutting tool which takes the form of an attachment for an electric jigsaw.
Australian Patent No. 650533 describes a nibbler tool designed to be attached to the chuck of an electric drill. The nibbler tool includes a clamp for clamping the tool to the nose portion of an electric drill. The tool has a hollow barrel with a longitudinally extending circular bore and slot having mounted therein a shuttle in the form of a cylindrical rod. A cutting anvil formed of hardened steel is mounted at one end of the barrel and is provided with a slot in alignment with the longitudinally extending slot of the barrel. A nibbler blade is attached to the shuttle which is adapted for reciprocating movement within the barrel by means of an attachment fitted to the drill chuck. A longitudinally adjustable foot is mounted on the barrel but is spaced therefrom by a foot blade. The foot enables the nibbler tool to cut shaped material such as corrugated iron.
The nibbler tool described in Australian Patent No. 650533 is the only tool currently available for cutting shaped material such as corrugated iron. However, there are a number of significant disadvantages with this tool. Firstly, the saw comprises a large number of parts, many of which must be individually machined, thus greatly increasing the overall cost and complexity of the tool. The slot provided in the anvil must be high precision cut to ensure that the nibbler blade provides a clean cut in the work piece. Furthermore, cutting is relatively slow as the nibbler blade only takes one nibble for each stroke of the blade. The sliding movement of the shuttle within the barrel and the blade within the slot of the anvil requires constant lubrication in order to reduce friction and heating of the tool.
Although the adjustable foot helps to retain the work piece in the vicinity of the nibbler blade, it does not provide adequate support for the work piece, which is still subject to significant vibration during cutting action of the nibbler tool. The work piece must typically be supported on a foam pad or the edge of a table or work bench. Hence, the nibbler tool of Patent No. 650533 is not sufficiently reliable and easy to use by tradesmen such as roofing specialists, who need to be able to cut corrugated iron in situ.
The present invention was developed with a view to providing a cutting tool of simple construction which is easy to use and which can reliably cut shaped material such as corrugated iron.
According to one aspect of the present invention there is provided a cutting tool comprising:
an elongate cutting blade;
an elongate housing adapted to slidably receive therein the cutting blade driven in a reciprocating manner, the housing having a blade support provided at a free end thereof in which the cutting blade is slidably supported, the housing being shaped so that the cutting blade does not engage the housing anywhere else along substantially its full length; and,
a work piece support extending from the free end of the housing and having a support member arranged to engage a work piece in a stabilising manner adjacent the free end of the housing when the cutting blade is cutting through the work piece in use.
Preferably said work piece support further comprises a thin elongate guide member connected to the housing and extending parallel to and adjacent the cutting blade where it protrudes from the free end of the housing, and arranged so as to pass through a cut in the work piece formed by the cutting blade and having the support member mounted thereon underneath the work piece. In a preferred embodiment said guide member also acts as a guide for the cutting blade and is adapted to receive the cutting blade in sliding engagement therewith whereby, in use, as the teeth on a front cutting edge of the cutting blade engage with the work piece, a rear edge of the cutting blade is slidably supported on said guide member.
Preferably said guide member is movably connected to the housing so that the length of the guide member extending from the free end of the housing can be adjusted, whereby the distance said support member is spaced from the free end of the housing is adjustable.
Advantageously said blade support is formed integral with said guide member, and comprises first and second guide walls forming a guide channel within which said cutting blade is slidably received.
In one embodiment said elongate housing is of rectangular cross-section and is adapted to fully enclose the cutting blade along the length of the housing. Advantageously said housing is formed with an aperture adjacent the free end through which any shavings drawn into the housing by the cutting blade can be ejected.
In another embodiment said elongate housing comprises a pair of rigid legs joined at both the free end of the housing and at the opposite end, said cutting blade being slidably received between the two legs.
Preferably said housing is adapted to be mounted on an electric jigsaw and said cutting blade is driven by the jigsaw in the same manner as a conventional jigsaw blade.